Historically, chemical mechanical planarization, also known as "CMP," has been developed for many uses in the semiconductor industry, like removing a thin top layer material from a semiconductor die.
A utilized VCMP machine, is illustrated in FIG. 1, and comprises: a wafer carrier 10 holding a semiconductor wafer 12 in a chemical slurry 14 presses against a course polishing pad 16 mounted on a platen or holder 18.
In operation, a VCMP machine works like a sanding machine and acid bath combined. To mechanically remove wafer material, wafer 12 is positionally fixed and held against pad 16 while platen or holder 18 vibrates. Slurry 14 is used to chemically remove the wafer material. Thus, it is understood why the process is called a vertical chemical mechanical planerization process.
FIG. 2 illustrates a cross-section of a wafer 12 comprising: a tungsten material 20 having a top layer 23, a few silicon-type material sections 22, and a wafer base 24.
FIG. 3 illustrates a cross-section of wafer 12 that demonstrates the goal sought when removing the top layer of material 23; leaving a desired smooth level top surface.